We propose to continue our studies of the conformations of prostaglandins (PG) by X-ray diffraction techniques in order to elucidate the relationship between their conformations and their antihypertensive activities. Our specific goals for the coming year include the determination of the structures of recently crystallized prostaglandins, including PGF2 beta and the PGF2 alpha analog, 17,18,19-trinor, 17-rho-chlorophenoxy PGF2 alpha (ICI 80996). We further propose to continue to test our hypothesis that the conformation of a prostaglandin is determined by its configuration at six principal loci on the molecule. Recent studies of the conformations of PGF2 alpha reveal that the configuration at the C9 ring position is critical to the conformations of the alpha-chain of the molecule, lending strong support to the hypothesis. In addition, we plan to correlate the conformational data resulting from our studies with similar currently available data in order to assess the possibility that existing binding data for prostaglandin receptors can be predicted by the conformational data.